Origin

Kryptonian scientist Doctor Xa-Du was convicted of conducting forbidden experiments in suspended animation which resulted in the deaths of those upon whom he was experimenting. He was sent to the Phantom Zone for his crimes, as was his wife Erndine Ze-Da, at a later date.

Dr. Xadu as Pa Kent in Jor-El's suit.

The pair managed to escape from the Phantom Zone but Superboy tricked them and exiled them to planet Exon which had a red sun. This meant of course that the Kryptonian villains had no super powers. Years later the pair returned, with a new power that worked when they gripped each other's hands. Superman imprisoned them on separate worlds in different galaxies.

The New 52

Origin

Being exiled.

Due to their contradictory experiences with suspended animation Xa-Du was condemned by the K-Council to be dematerialized and exiled for eternity to the Phantom Zone,where he would be unable to feel pain and cause pain to any other person again.

Taking advantage of the long years in exile he studied Phantom Zone's secrets to develop Ecto-Technology that would allow others to walk amongst the living world, thus creating the Ecto-Suit which is powered by pure consciousness.

Major Story Arcs

The Ghost in the Fortress of Solitude

Pulled back to the Phantom Zone.

Hearing a noise Superman is attracted to the room where placed Kandor and a Phantom Zone projector,but was caught off guard by Xa-Du that used the projector to banish him to the Phantom Zone,fulfilling his revenge against House of El and giving him time to plan his attack on Earth.

Inside the Phantom Zone he struggles to survive the attacks of other prisoners, until be helped by Phantom Stranger who explained that Xa-Du's Ecto-suit is powered by willpower and that only through willpower could take control of the suit and turn back the projector to escape. So using his willpower Superman was able to take control over the suit, which pulled Xa-Du to back into the Zone.

At the end of days

Shortly after it is revealed that he accepted the offer of the Little Man joining his Anti-Superman Army.

Breaking kryptonian's sunstones .

Alongside Anti-Superman Army invades the first Fortress of Solitude (a Brainiac Ship) to steal the kryptonite engine from Kal-EL's Escape Pod so the Little Man could create another isotopes from this material.

Later is seen fighting Superman in Metropolis.

Superman: Doomed

While following Krypto in Doomsday's trail to the Phantom Zone ,Batman and Wonder Woman found Dr. Xa-Du using a device which drains energy from dimensional rifts left by Doomsday when it broke free of the Phantom Zone.

Shortly after is captured by Wonder Woman and locked away in a special cage to restrain their powers, so Batman, Shay Veritas and Harrow created a plan to remove all kryptonite's particles off the planet giving Superman control over his body again. Harrow pinned Xa-Du between dimensons,while Luthor and Shay Veritas tap into his ecto-technology to turn kryptonite intangible and thus open several portals to other dimensions.

Getting rid of Harrow, he teleports away.

Superman's Joker

Changing his own size.

A series of mysterious attacks to people and creatures directly or indirectly related to Superman cause panic to everyone, clueless of who can be the murderer Clarks asks Batman for help. analyzing the recent attacks Batman says he is facing an obsessive, insane and remorseless assassin,in other words Superman got to himself a Joker. Over time the attacks get more and more serious with no traces of the killer's strike options nor any leads to they're identity, a final desperate bid leads the duo to draw out the apathetic killer using the last person both his identities have had contact with; Lois Lane. Which almost worked only for it to backfire horribly and instead have the target changed to Batman, who just barely survives by having some Kryptonite stashed in his suite; which Kara Zor-El comments on later. With this latest interaction they find whatever the ammo said killer is using isn't what it seems; in reality it was a Kandorian used as a microscopic super bullet. With this knowledge in mind Superman, Batman and Supergirl pay visit to the Bottled City of Kandor which was last located somewhere out in the Black Sand Desert of Iceland.

After a brief intro both from how kandor survived by the Phantom King's hand and via microscope view of a ruined city, Bruce surmises that Kandor is under military police state and that any number of it's citizens have become a deranged mass murderer. As Dr. Palmer shrinks the Ant-Farm to microscopic size to enter the city from from beneath it providing the trio with size shifter belts to scale up to Kandorian size once within. On inside they notice a small garrison of it's soldiers all marching in sync all under the direct control of someone. As it turns out Xa-Du had utilized a science he had been perfecting Called the Living Death to fool the slumbering inhabitants into believing it was Jor-El who betrayed all of Krypton to it's fiery demise as he framed, blamed and banished his peer to the Phantom Zone just before saving Kandor only to shrink and bottle it. Leaving it in the care of his believed to be deranged son Kal-El of Krypton. After Kara, Kal and Batman smash the only exit in and out of the bottle city Superman finally pieces it together just after Xa-Du finally materializes as a towering giant above the cityscape, who happens to call in the rest of they're now super powered kin under sway of the Living Death. As the kryptonian duo battled they're estranged family batman made the scene brandishing a weapon to use against them, a device called a red sun generator he had developed using inklings of Kryptons red star.

As he explained the effects of it's power depressant were only temporary however he was flash fried by Mara's heat vision, or so it would seem, much to a gloating Phantom King who watched Kal-El lement the loss of his best friend and trusted confidant as they're family resumed raining down upon them once again. Only for Kal-El to finally shed his compassion's and put them down right at the time Xa-Du took control of the rest of Kandor's denizens feeding them the yellow sunlight they needed to finally do away with the children of El, however Superman managed to overload Batman's red solar generator empowering most of them indefinitely. Moving in for the kill after having tormented him enough, Xa-Du is abruptly undermined when the circuitry streamlining into his brain is suddenly destroyed by the Ant-Farm bursting from within his head sending him back to the zone. Batman faked his death by shrinking to atomic scale just before he was nearly incinerated, then it was a simple yet difficult matter of mapping out the cybernetic components within Kings's mind in order to disrupt his hold.

Even with the threat vanquished and most of the Kandorians freed, Xa-Du's venomous bane still lingers as nearly 3% of the kandorians were near irreparably warped by his brainwashing still beliving the lie and murderously cursing the El family name. While he had left his mark on everyone that day the Phantom King could still be seen back within his prison plotting new vengeance against Krypton's Last Son stating his failure only made him stronger.

Alternate Deadlock

Powers & Abilities

Due to being Kryptonian Xa-Du possess all abilities present in a Kryptonian under a Yellow Sun. However, due to still being a prisoner in the Phantom Zone and ,so if loses contact with the suit he will pulled back into the Phantom Zone.

Teleporting.

Superhuman Strength: He showed enough strength to go toe to toe with Superman and even break kryptonian's sunstones.

Superhuman Durability

Invulnerability

Superhuman Speed

Superhuman Stamina

Superhuman Senses

Freeze Breath

Heat Vision

Flight

Teleportation: Unlike other Kryptonians he has the ability to teleport, but it is still unknown whether it is a power of himself or something developed during exile in the Phantom Zone.

Psionic Manipulation: Either through his time adjusting to the Phantom Zone or his use of the ecto-tech which enhances his will to project himself into physical reality. Xa-Du has shown to be proficient in mind-over matter able to will enmass a city of enraged kryptonians through the usage of his technologies; to do his bidding or plant subliminal suggestion within three of the worlds most deadly criminals as easily as he can in normal people.

Equipment

Ecto-Suit: A kryptonian composite body armor he had created in order to be able to project and move about within the physical world by enhancing and materializing himself through projecting willpower.

Living Death: An artificial krypronian virus used to control people with right down to the conscious and subconcious levels, enabling him to rewrite a persons very memories at will to bend them towards his way of thinking.

Weakness

Ecto-Suit dependece: In order to able to walk among the living he needs to be in direct contact with his suit,but if loses contact with he will be pulled back into the Phantom Zone.

Willpower: His armor can be disabled or controlled by others with willpower, greater than his

Blue Kryptonite: He is apparently immune to green Kryptonite, but the Blue Kryptonite is extremely lethal because it can kill a spirit.